6-(benzoylureido)-penicillanic acid derivatives



United States Patent 3,180,863 6-(BENZOYLUREIDO)-PENICILLANIC ACIDDERIVATIVES Takayuki Naito, Nakamachi, Okazaki-shi, Japan, assignor toEristol-Banyu Research Institute, Ltd., Tokyo, Japan, a Japanesecorporation No Drawing. Filed May 1, 1963, Ser. No. 277,125

14 Claims. (Cl. 260-2391) 7 effective against numerous so -calledresistant strains of bacteria, e.-g. benzylpenicillin-resistantstrainslof Staphyl oc'occus aureus (Microcdccus pyrogenes .var. aurehs).

It is the object of the present invention to provide novel compoundswhich are effective against such resistant strains. It' is a furtherobject. of the present invention to provide agents which actuallyinhibit penicillinase and are thus also useful adjuvants for penicillinssuch as benzylpenicillin.

The objects of the present invention have been achieved by theprovision, according to the present invention, of a member selected fromthe group consisting of an acid of the formula wherein R R R and R areeach a member selected from the group consisting of hydrogen, chloro,bromo, iodo, trifluoromethyl, phenyl, nitro, (lower)alkyl and(lower)alkoxy but only one R group may represent phenyl andnontoxic,"pharmaceutically acceptable salts thereof. r r

The nontoxic, pharmaceutically acceptable salts include metallic saltssuch as sodium, potassium, calcium and aluminum, the ammonium salt andsubstituted ammonium salts, e.g., salts of-such nontoxic amines astrialkylamines, including triethylamine, procaine, dibenzylarnine, N-benzylbeta-phenethylamine, l-ephenamine, N,N-dibenzylethylenediamine,dehydroabietylamine, N,N'-bis-dehydroabietylethylenediamine,-N(lower)alkylpiperidines, e.g. N-ethylpiperidine, and other. amines whichhave been used to form salts wth benzylpenicillin; The term (lower)alkylas used herein means both straight and branched chain aliphatichydrocarbon radicals having from one to ten carbon atoms such as methyl,ethyl, propyl, isopropyl, butyl, isobutyl, t-buty1, amyl, hexyl,Z-ethylhexyl, heptyl, decyl, etc. Similarly, where the term (lower) isused as part of the description of another group, e.g. (lower) alkoxy itrefers-to the alkyl portion of such group which is therefore asdescribed above in connection with (l0wer)alkyl. Also included withinthe scope of the present invention are easily hydrolyzed esters andamides which are converted to. the free acid form by chemicalorenzymatic hydrolysis.

The preferred compound of the present invention has the formula abovewherein R R R and R are each hydrogen and is named 6(benzoylureido)penicillanic acid.

3,180,863 Patented Apr. 27, 1965 'ice . 2 Distantly related compoundshave been describedby Perron et al. (J. Org. Chem. 26, 3365-3367, 1961)and in. British Patent 873,533-and German Patent 1,141,640.

Much more closely relatedgcompounds have been pre-,

pared by the present inventor and found, as set forth in detailbelow, tolack the ability to inhibit penicillinresistant Staphylococci whichcharacterizes the .compounds of the present invention. Thus the minimuminhibitory concentration (M.I.C.) in meg/ml. versus two highlybenzylpenicillin-resistant strains of Staphylococci (BX-1633 and 52-75)was determined in vitro for various compounds of the formula o. s\ /CHR- C JNH( LNH-CHCH o with the following results 1 M.I.O.inmcg./ml.

Compound VS- VS. 1033a 52-75 ofln'vo-o m- 100 100 II II 0 CH3 25 2550-100 100- 100 50 y 50 100 100 50 25-50 12.5 12. 5-25 From thisinformation the unusual activity of 6- (benzo ylureido)penicillanic acidagainst a strongly resistant Staphylococcus is readilyapparent. Thissame compound is also quite stable to acid (having a half-life of 24hours at pH 2 and 37 C. compared to 1.3 hours for benzyl penicillin in acomparative experiment) and when given parenterally to mice alsoprotects against an overwhelming infection of the same Staphylococcus1633-2 at a mini-J mum does about equal to the minimum dose required foroxacillin. Protection, is also provided by higher doses given by theoral route. ,The compounds of the present invention are prepared by thereaction of the appropriatebenzoylisocyanate, i.e. a compound having theformula R1 15 p v (i1-NC O wherein R R ,-R and R have the meaning setforth above, with 6-aminopenicillanic acid, preferably in the form of aneasily hydrolyzed ester or of a salt of an' as the triethylamine salt,the product is converted to the free acid form and thence to other saltsin the manner used with benzylpenicillin and other penicillins. Thus,treatment of such a triethylamine compound in water with sodiumhydroxide converts it to the sodium salt and the triethylamine may beremoved by extraction, as with toluene. Treatment of the sodium saltwith strong aqueous acid converts the compoundto the acid form, whichcan be converted to other amine salts, e.g. a procaine salt, by reactionwith the amine base. Salts so formed are isolated by lyophilization or,if the product is insoluble, by filtration. A preferred method ofisolating the product as a crystalline potassium salt comprisesextracting the product from an acidic, aqueous solution (e.g. pH 2) intoa water-immiscible solvent such as n-butanol or diethyl ether, dryingand adding at least one equivalent of a solution of potassium2-ethylhexanoate (e.g.', 0.373 g./ml.) in dry n-butanol. The potassiumsalt forms precipitates, usually in crystalline form, and is collectedby filtration or decantation.

The benzoylisocyanates are prepared from the corresponding benzoic acidchlorides either by reaction with silver cyanate according to Billeter,Ber. 36, 3213 (1903), or Hill, I. Am. Chem. Soc. 62, 1595 (1940), or byreaction with ammonia to form the amide followed by reaction of theamide with oxalyl chloride according to Speziale and Smith, J. Org.Chem. 27, 3742 (1962).

The substituted benzoyl chlorides (and the acids from which they areprepared, as by reaction with thionyl chloride) required above areprepared by a variety of methods which are common in the art. Most ofthese acids and acid chlorides are described in the prior art and manyof them are commercially available. Detailed discussion of methods forthe preparation of these starting materials are found in such referenceworks as the Chemistry of Carbon Compounds, E. H. Rodd, editor (1956),Elscvier Publishing Company, particularly in volumes IIIA and IIIB.

The following examples will serve to illustrate this invention withoutlimiting it thereto.

Example 1 Benzoyl chloride (84 g.; 0.6 mole) was added dropwise to 200ml. of concentrated ammonium hydroxide with vigorous stirring andcooling. After the addition was completed stirring was continued forhalf an hour and the white precipitate of benzamide was collected'byfiltration, washed thoroughly with 10% aqueous ammonium hydroxide andthen with water and found to weigh 64 g. and to melt at 121-1225 C.after recrystallization from ethanol.

Oxalyl chloride (35 g.; 0.28 mole) was added to a suspension of 24 g.(0.2 mole) benzamide in 80 ml. dry ethylene dichloride at to 5 C. andthe mixture was refluxed until a clear solution was obtained, whichrequired four hours. Distillation in vacuo gave 24 g. benzoylisocyanate,B.P. 110 C./31-32 mm., as a colorless liquid.

A suspension of 21.6 g. (0.1 mole) of 6-aminopenicillanic acid in 200ml. dry methylene chloride was cooled, 30 ml. triethylamine was addedand the mixture was stirred for ane hour at 20 C. Insoluble material (2g., mainly 6-aminopenicillanic acid) was removed by filtration and thefiltrate containing triethylammonium 6-aminopenicillanate was chilled toabout 0 C. and stirred. To this solution there was added dropwise asolution of 15 g. (0.1 mole) benzoylisocyanate in 30 ml. dry methylenechloride while maintaining the temperature below 5 C. After thataddition the mixture was stirred for two hours at 0 C. The reactionmixture containing the product, triethylammonium6-(benzoylureido)penicillanate, was extracted with two 200 ml. portionsof water and the separated aqueous phases containing the product werethen combined, covered with 200 ml. ethyl acetate, chilled below 0 C.,vigorously stirred and acidified to pH 2 with dilute sulfuric acid, Theorganic solvent layer containing l 6-(benzoylureido)penicillanic acidwas separated and the aqueous phase was again extracted with anadditional 200 ml. ethyl acetate. The organic solvent extracts werecombined, washed with two ml. portions of cold water and dried overanhydrous sodium sulfate. The addition of 30 ml. of a 48% by weightsolution of sodium 2-ethylhexanoate in dry n-butanol precipitated theproduct, sodium 6-(benzoylureido)penicillanate. The solution containingthe precipitated product was concentrated by distillation in vacuo to avolume of 150200 ml. and one liter of dry diethyl ether was addedthereto. The precipitated product was collected by filtration, washedwith dry ether, dried in vacuo andfound to weigh 24 g. The product was awhite powder which was found to contain a ,B -lactam ring by infraredanalysis, to be soluble in water and to inhibit Staph. aureus Smith at aconcentration of about 1 meg/ml. and to exhibit versus Staph. aureusSmith in mice a CD of 1.5 mgm./kg. upon intramuscular injection and 18.5mgm./ kg. upon oral administration.

Example 2 In the procedure of Example 1 there is'substituted for thebenzoyl chloride an equimolar amount of the acid chloride prepared bytreatment with thionyl chloride of 4-nitrobenzoic acid (M.P. 242 C.),2-cl1'lorobenzoic acid (M.P. 142 C.), Z-methylbenzoic acid (0- toluicacid; M.P. 104v C.), 3,4,5-trimethoxybenzoic acid (M.P. 168 C.),4-methylbenzoic acid (p-toluic acid; M.P. 179 C.), 4-chlorobenzoic acid(M.P. 243 C.), 3,4,- dichlorobenzoic acid (M.P. 208209 C.),3-nitrobenzoic acid (M.P. 141 C.), 2,4,6-trimethoxybenzoic acid, 4-ethoxybenzoic acid (M.P. 195 C.), 2,6-dimethoxybenzoic acid,2,4,6-trimethylbenzoic acid (M.P. 152 C.), 2,6,- dichlorobenzoic acid(M.P. 139 C.), 2,6-diethoxybenzoic acid (M.P. -132 C.),2,6-di-n-butoxybenzoic acid (M.P. 81-83 C.), 2,3,6-trimethoxybenzoicacid, 2,4,6- tribromobenzoic acid, 2,6-di-n-propoxybenzoic acid (M.P.5456 C.), 2,6-dimeth0xy-4-methylbenzoic acid, 4,6-diethyl-2-methoxybenzoic acid (M.P. 112113 C.), 2-ethoxy-G-methoxybenzoic acid, 2-phenylbenzoic acid (M.P. 114 C.),2-methoxybenzoic acid (M.P. 98 C.), 2,6- dimethylbenzoic acid (M.P. 116C.), 2-chloro-6-methylbenzoic acid, 2,6-dimethoxy-3-nitrobenzoic acid(M.P. 132 C.), 3,5-dichloro-2,6-dimethoxybenzoic acid (M.P. 104 C.),3,5-dibromo-2,6-dimethoxybenzoic acid (M.P. 111 C.),3-bromo-2,6-dimethoxybenzoic acid (M.P. C.),3-chloro-2,6-dimethoxybenzoic acid (M.P. 132 C.),3,5-diiodo-2,6-dimethoxybenz0ic acid (M.P. 136138 C.),3-iodo-2,6-dimethoxybenzoic acid (M.P. 162 C.), 4-trifluoromethylbenzoicacid, 4-isopropylbenzoic acid (M.P. 116 C.), and 4-iodobenzoic acid(M.P. 269 C.), respectively, to produce the acids 6-(4-nitrobenzoylureido penicillanic acid,

6- 2'-chlorobenzoylureido penicillanic acid,

6- 2-methylbenzoylureido penicillanic acid,

6- 3',4,5'-trimethoxybenzoylureido penicillanic acid,

6- (4-methylbenzoylureido penicillanic acid,

6- (4'-chlorobenzoylureido)penicillanic acid,

6- 3 ',4-dichlorobenzoylureido penicillanic acid,

6- (3 '-nitrobenzoylureido penicillanic acid,

6- 2,4,6-trimethoxybenzoylureido penicillanic acid,

6- 4'-ethoxybenzoylureido penicillanic acid,

6- 2',6-dimethoxybenzoylureido penicillanic acid,

6- 2',4,6'-trimethylbenzoylureido penicillanic acid,

6-(2,6'-dichlorobenzoylureido)pencillanic acid,

6- 2,6'-diethoxybenzoylureido penicillanic acid,

6- 2',6'-di-n-butoxybenzoylureido penicillanic acid,

6- 2',3 ,6-trimethoxybenzoylureido penicillanic acid, I

6- (2,4',6'-tribromobenzoylureido) penicillanic acid,

6- (2,6-di-n-propoxybenzoylureido penicillanic acid,

6- (2',6-dimethoxy-4'-methylbenzoylureido (penicillanic acid,

6- (4,6'-diethyl-2-methoxybenzoylureido penicillanic acid,

which are isolated as their water-soluble sodium salts and found tocontain the fi-lactam ring structure as shown by infrared analysis andto inhibit Gram-positive bacteria, e.g. Staph. aureus Smith at lowconcentrations.

I claim:

1. A compound selected from the group consisting of an acid of theformula wherein R R R and R are each a member selected from the groupconsisting of hydrogen, chloro, bromo,

iodo, trifluoromethyl, phenyl, nitro, (lower)alkyl and (lower)alkoxy butonly one R group may represent phenyl and nontoxic, pharmaceuticallyacceptable salts thereof.

2. A compound of the formula wherein R and R represent (lower) alkyl.

3. A compound of the formula 0: -N--CHCOOH wherein R and R represent(lower) alkoxy.

4. A compound of the formula O=C-NCECOOH wherein R and R representohl-oro. 5. A compound of the formula wherein R represents (lower)a1ky1.6. A compound of the formula wherein R represents (lower)alkoxy.

7. A compound of the formula 1) CH 0: N- 1100011 wherein R representschloro.

8- A compound of the formula wherein R represents phenyl.

9. A compound of the formula 0: --N HCOOH wherein R representstrifi-uoromethyl.

10. 6-(benzoylureido)penicillanic acid. 11.6-(2'-phenylbenzoylureido)penicillanic acid. 12. 6-(2',6'dimethoxybenzoylureido)penicillanic acid. 13.6-(4'-chlorobenzoy1ureido)penicillanic acid. 14. 6 (4'trifluoromethylbenzoylureido) penicillanic acid.

References Cited by the Examiner UNITED STATES PATENTS 2/64 Wallhauseret al 260239.1

NICHOLAS S. RIZZO, Primary Examiner.

1. A COMPOUND SELECTED FROM THE GROUP CONSISTING OF AN ACID OF THEFORMULA